1. Technical Field
The present invention relates to a lighting device for a vehicle using a light-emitting element, such as a light-emitting diode, as a light source.
2. Related Art
Recently, a lighting device has been developed for a vehicle, such as a headlamp, using a light-emitting element, such as an LED, as a light source.
Disclosed in Patent Document 1 is a lighting device for a vehicle including a first reflection surface which reflects light from a light-emitting element disposed toward the lateral side of the lighting device toward the rear side of the lighting device, and a second reflection surface which reflects the light reflected from the first reflection surface toward the front side of the lighting device. In the lighting device disclosed in Patent Document 1, the first reflection surface is a rotary elliptic surface having the light-emitting center of the light-emitting element as a first focus and a point located next to the first focus as a second focus. In addition, the second reflection surface is a rotary parabolic surface having the second focus of the rotary elliptic surface as a focus.
Disclosed in Patent Document 2 is a lighting device for a vehicle having the same configuration as the above-described lighting device, but not having the light-emitting element as a light source.
[Patent Document 1] JP-A-2001-332104
[Patent Document 2] JP-A-4-212202
By using the lighting device for a vehicle disposed in Patent Document 1, or replacing the light source of the lighting device for a vehicle disclosed in Patent Document 2 with a light-emitting element, it is possible to increase the utilization rate of light flux from the light-emitting element and then to control irradiation of light.
However, the lighting device for a vehicle disclosed in Patent Document 1 and Patent Document 2 reflects light from the light source, and the light is converged at the second focus of the rotary elliptic surface forming the surface shape of the first reflection surface, and then the light is incident on the second reflection surface as a diverging light from the second focus. Consequently, the width in the forward and backward direction of the lighting device becomes large. For this reason, there is a problem in which a lighting device cannot be provided when a space for mounting the lighting device in the vehicle does not provide sufficient width in the forward and backward direction.